3-Season 30 ° F / - 1 ° A great year-round bag or a three-season choice for cold sleepers, this bag combines HeatSync continuous-filament insulation with Flex™ technology to deliver tough to beat quality in a light, durable design.
For superior comfort and heat retention, Sierra Designs incorporates Flex technology into several insulated jackets and sleeping bags. With elastic built into the baffles of both down and synthetic jackets and bags, Flex technology hugs the body, eliminates dead air space, and keeps warm air close to the body. And beyond just keeping you warmer, Flex jackets and sleeping bags move with you for better mobility and a more comfortable night’s sleep.